This invention relates to the field of passive integrated transponder tags, and specifically to a passive integrated transponder tag having a unitary antenna core.
The use of Passive Integrated Transponder (PIT) tags which may be embedded in or attached to items to be tracked and accounted for has been widespread for some time. These commonly known PIT tag systems generally comprise one or more antenna coils so positioned as to generate a field of radiated electromagnetic energy within which the tagged item or object must pass. As generally deployed, such systems are used to track and/or count animals within which a PIT tag has been subcutaneously embedded or externally affixed.
As the PIT tag traverses the radiated field of electromagnetic energy, it is energized in a manner known in the art. The PIT tag uses this energyxe2x80x94which is typically stored in a capacitive elementxe2x80x94to power a transmission circuit which emits a unique PIT tag identification signal that is detected by the aforementioned antenna element. The identification signal detected by the antenna element is then transmitted to remote processing equipment which decodes the detected signal and uses this decoded information for the purposes of counting, tracking or otherwise maintaining records pertinent to the population of items or animals being tracked by said system.
PIT tags, or transponders, of the type used for object identification, and particularly those which are implantable into living creatures, such as livestock, are well known in the art. Most such PIT tags comprise a coil, which serves as a receiving antenna, for receiving interrogation signals to activate the transponder and for receiving power for its operations. The same antenna is used to transmit the identification signal. An integrated circuit, housed in an art-recognized integrated circuit package, is also provided for performing the circuit functions, including detection of the interrogation signal, conversion of the received signal to DC for powering of the transmitter operations, storage and provision of an identification code, generation of the transmission signal frequency, and modulation of the transmitted signal in accordance with the code and its transmission. The circuit divides the interrogation signal frequency by plural divisors to generate two frequencies which are used to provide a frequency-shift-keyed output signal, the transmission frequency varying in accordance with the stored identification signal. The transponder may be encapsulated in glass or a similarly durable material, as a matter of design choice. It may be supplied together with a disposable cannula for convenient syringe implantation into an animal. Together with essentially conventional interrogator and data storage equipment, a complete animal monitoring system can be provided, suitable for monitoring migratory movements of wild animals as well as laboratory animals, pets and livestock.
PIT tags of the type used for object identification, and particularly those which are implantable into living creatures, such as livestock, are very small and have inherent size restrictions that must be considered in their design and manufacture. Over the years, different size PIT tags were tested and used throughout the industry. Eventually, in the market for animal identification through implantable PIT tags especially, the size became more standardized. Today, one of the more standard sizes in this field is a PIT tag 12 mm long and 2.07 mm wide. Most of the major studies in companion animals and fish applications were carried out with such sized PIT tags. Given such a size standardization, a need in the art has arisen to increase the operating range or performance of the PIT tag without increasing its size.
As described in the prior art, PIT tags have generally been constructed in one of two ways. In the first, the PIT tags are built in subassemblies, such as one subassembly comprising the antenna having loose wire leads and another subassembly comprising the Integrated Circuit (IC) and a capacitor mounted on a Printed Circuit Board (PCB). See, for example, U.S. Pat. No. 5,211,129, which is assigned to the same assignee as the present application, and which is hereby incorporated by reference. The two subassemblies are then electrically and mechanically connected. This approach does provide some advantages, including the use of standard manufacturing machinery as well as the ability to permit design changes quickly and easily during the manufacturing process. However, this approach also has some disadvantages, such as it tends to be labor intensive because much of the assembly of the subcomponents must be done manually, for example, connecting the antenna leads to the IC, and the entire manufacturing process tends to be costly and timely due in part to the number of manufacturing steps involved.
In a second approach, the antenna leads are directly connected to the IC during the manufacturing process. See for example, U.S. Pat. Nos. 5,223,851 and 5,281,855, each of which is incorporated herein by reference. One advantage of such an approach is that the manufacturing process is more fully automated, thus saving time. However, due in part to the small size of the components involved, the machines that directly connect the antenna leads to the IC tend to be expensive and often need maintenance or supervision by a dedicated expert. Further, another disadvantage of this system is that because the antenna leads are connected directly to the IC, it is difficult and expensive to substitute alternate types of ICs or capacitors on the final PIT tag without significant changes in the manufacturing assembly process. Nonetheless, in the prior art the core and IC support subassemblies are not unitary but rather are multi-part assemblies made integral by joining the parts together.
It would therefore be advantageous for a PIT tag to be developed which would alleviate shortcomings of the prior art. The present invention provides a solution.
The PIT tag of the present invention generally comprises a unitary core that extends substantially the entire length of the PIT tag. As used herein, the term unitary is given its ordinary meaning and means a one-piece core. In a preferred embodiment the unitary core generally comprises a cylindrical portion for receiving the antenna coil at one end and a flattened portion for permitting or housing the electrical connection between the integrated circuit and/or capacitor and the antenna coil at the other end. In a preferred embodiment the flattened portion of the core is formed with an integral pair of metalization layers or pads. With the core so constructed, the leads from the antenna coil can be electrically connected to the metalization layers during the manufacturing process. As discussed herein, it is assumed that the Integrated Circuit (IC) is housed in an art-recognized IC package, thus, unless otherwise specified, the term IC as used herein refers not only to the circuitry but to the IC package and leads typically present with ICs used in conjunction with the PIT technology described herein.
By providing metalization layers on the core itself, the integrated circuit and/or capacitor can be easily electrically connected to the metalization layers in any of a number of art-recognized methods. Once connected to the metalization layers, the integrated circuit is electrically connected to the antenna coil as well. With the core so constructed, the unitary core serves as the support for the integrated circuit and/or capacitor and also permits the electrical connection between the integrated circuit and/or capacitor and the antenna coil to be accomplished in a quicker and less costly manner than that of the prior art.
As one of skill in the art will recognize, by electrically connecting the antenna coil to the metalization layer, as opposed to the integrated circuit, machinery can be more readily utilized and the manufacturing process can be more fully automated. Further, by electrically connecting the integrated circuit to the metalization layer, without having to attach the integrated circuit directly to the antenna coil leads, it becomes easier and less expensive to customize the PIT tags by permitting the substitution of different integrated circuits and/or capacitors on the metalization layer, thereby permitting customized PIT tags to be manufactured more easily.
Further, the unitary core of the present invention permits a larger volume of core material to be used in a standard-sized PIT tag, or any size of PIT tag for that matter. As one of skill in the art will recognize, one of the factors affecting the strength of an electromagnetic field is the size and material of the core. By increasing the amount of core material in the PIT tag, without increasing the overall size of the PIT tag, the PIT tag of the present invention provides for greater strength of the magnetic filed of the antenna coil, thereby increasing the operational range of the PIT tag.
Further, as one of skill in the art will recognize, by utilizing a unitary core design as described herein, the PIT tag may be able to sustain more shock and vibration than conventional PIT tags because the flattened portion of the core physically supports the integrated circuit and/or capacitor.
Further, as one of skill in the art will recognize, by utilizing a unitary core design as described herein, the integrated circuit used in the PIT tag can be of the flip-chip technology with a surface mounting capacitor connected with conductive glue and cured with heat, or with conventional soldering, or any other art-recognized method.
Other objects and features of the present invention will become apparent from the following detailed description considering conjunction with the accompanying drawing figures. It is to be understood, however, that the drawings, which are not to scale, are designed solely for the purpose of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims.